1. Field of the Invention
The present invention relates to a display device and a manufacturing method thereof.
2. Description of the Related Art
Recently, various types of display devices have been developed due to a demand for a reduction in thickness and an increase in definition of a display device. For example, an in-plane switching (IPS) mode liquid crystal display device is known as the display device.
FIG. 8 is a cross-sectional view showing one example of a pixel region provided in a conventional IPS mode liquid crystal display device. As shown in FIG. 8, in order to meet the demand for a reduction in thickness and an increase in definition of a display device, the structure of the conventional IPS mode liquid crystal display device is complicated. Because of the complicated structure, a manufacturing process of the display device is also complicated.
For example, one example of a manufacturing method of the IPS mode liquid crystal display device shown in FIG. 8 includes a lot of steps as follows: forming a gate electrode 4a, a gate insulating film 10, a semiconductor film 8, a source electrode 2a made of, for example, a metal, and a drain electrode 3a made of, for example, a metal on a substrate 9; thereafter forming a passivation film 11 which is an insulating film; forming common electrodes 7a on the upper surface of the passivation film 11; further forming an interlayer insulating film 12 which is another insulating film; forming a through hole 13 penetrating through the passivation film 11 and the interlayer insulating film 12 so as to electrically connect the source electrode 2a to the below-mentioned pixel electrodes 6; and further forming the pixel electrodes 6 using a transparent conductive material such as indium tin oxide (ITO). Such a conventional IPS mode liquid crystal display device is disclosed in, for example, JP 2009-192883 A.